Magnetic properties of YMn2 and related compounds studied by μSR

Zero, longitudinal and transverse field μSR was carried out between 3 and 250 K in YMn2, Y0.9Tb0.1Mn2, Y0.98Sc0.02Mn2 and TbMn2. The data had to be analyzed in the frame of electronic-nuclear double relaxation. The dynamics of Mn magnetic moments in the paramagnetic state is typical for an itinerant antiferromagnet approaching magnetic order. This behavior is suppressed abruptly when the first-order transition occurs. In all samples, a part enters a randomly ordered (spin glass like) magnetic state within a certain temperature range above TN as an outcome of frustration. The temperature range of existence and the fraction of the sample taking part in this state is enhanced by the presence of Tb3+ paramagnetic ions and also by the lattice pressure in the Sc doped compound. It is suspected that muon dynamics makes the extraction of information on magnetic relaxation questionable above 150-180 K. (orig.)